Photosensitive material and method of lithography

ABSTRACT

Photosensitive materials and method of forming a pattern that include providing a composition of a component of a photosensitive material that is operable to float to a top region of a layer formed from the photosensitive material. In an example, a photosensitive layer includes a first component having a fluorine atom (e.g., alkyl fluoride group). After forming the photosensitive layer, the first component floats to a top surface of the photosensitive layer. Thereafter, the photosensitive layer is patterned.

BACKGROUND

The semiconductor integrated circuit (IC) industry has experienced rapidgrowth. Technological advances in IC materials, design, and fabricationtools have produced generations of ICs where each generation has smallerand more complex circuits than the previous generation. In the course ofthese advances, fabrication methods, tools, and materials have struggledto realize the desire for smaller feature sizes.

Lithography is a mechanism by which a pattern is projected onto asubstrate, such as a semiconductor wafer, having a photosensitive layerformed thereon. The pattern is typically induced by passing radiationthrough a patterned photomask. Though lithography tools and methods haveexperienced significant advances in decreasing the line width of animaged element, further advances may be desired. For example, theprofile of the imaged feature of photosensitive material may lack thefidelity to the pattern required to accurately reproduce the desiredpattern on the substrate. For example, unwanted, residual photosensitivematerial may remain after imaging and development; or portions of thephotosensitive material needed to perform as a masking element may beremoved or otherwise damaged.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It isemphasized that, in accordance with the standard practice in theindustry, various features are not drawn to scale. In fact, thedimensions of the various features may be arbitrarily increased orreduced for clarity of discussion.

FIGS. 1, 2, 3, and 4 are cross-sectional views of prior art featuresformed of a photosensitive material

FIGS. 5-9 are cross-sectional views of exemplary embodiments devicesfabricated according to one or more aspects of the present disclosure.

FIG. 10 is a flow chart illustrating an embodiment of a method offorming a patterned layer on a substrate according to one or moreaspects of the present disclosure.

DETAILED DESCRIPTION

It is to be understood that the following disclosure provides manydifferent embodiments, or examples, for implementing different featuresof the invention. Specific examples of components and arrangements aredescribed below to simplify the present disclosure. These are, ofcourse, merely examples and are not intended to be limiting. Forexample, though described herein as a photolithography method configuredto fabricate semiconductor devices, any photolithography method orsystem may benefit from the disclosure including, for example, forTFT-LCD fabrication, and/or other photolithography processes known inthe art. Moreover, the formation of a first feature over or on a secondfeature in the description that follows may include embodiments in whichthe first and second features are formed in direct contact, and may alsoinclude embodiments in which additional features may be formedinterposing the first and second features, such that the first andsecond features may not be in direct contact. Various features may bearbitrarily drawn in different scales for simplicity and clarity.

Photosensitive materials are typically used to pattern target layers,for example, provided on a semiconductor substrate, in order to form adevice or portion thereof. One photosensitive material is chemicalamplify photoresist or CAR. For chemical amplify resist, a photoacidgenerator (PAG) will become an acid after exposure to radiation. Theacid will initiate the leaving of acid labile groups (ALG) of thepolymer during the post-exposure bake (PEB) process. The leaving of theALG will produce an acid for initiating leaving of subsequent ALG fromthe polymer. Such a chain reaction will be terminated only when the acidproduced comes in contact with a base, also referred to as a basequencher or quencher. When the ALG leaves the polymer of the resist, thebranch unit of the polymer will be changed to carboxylic group thatincreases the polymer solubility to a positive tone developer; thus,allowing the irradiated area of the resist to be removed by a developer,while the non-irradiated area remains insoluble and becomes a maskingelement for subsequent processes. The PAG and the quencher are typicallyprovided in a solvent. (Typical solvents include xylene, acetates,and/or other suitable solvents.) Other components of the photosensitivematerial may also or alternatively be present including photo basegenerator (PBG), photo decompose quencher (PDQ), dyes, wetting agents,coating aids, amines, adhesion promoters, and/or other suitablecomponents.

It is desired that the acid produced by the PAG and the base produced bythe quencher should be kept in balance to keep the profile of theresultant masking element feature having a fidelity to the patternincluding, for example, straight sidewalls. If the acid concentration istoo strong, the space dimensions between features (space CD) can becomeoverly large. Conversely, if the quencher loading is too high, the spaceCD can become too small. Thus, what is needed is a material and methodof keeping an acceptable loading between acid and base in thephotoresist material to provide pattern fidelity.

Illustrated in FIGS. 1, 2, 3 and 4 are cross-sectional views of deviceshaving various profile issues of a feature formed on a substrate.Specifically, the feature is a patterned photosensitive layer orphotoresist. The resist profile is disadvantageous in each of thedevices 100, 200, 300 and 400 due to lack of fidelity to the desiredpattern. Device 100, shown in FIG. 1, illustrates a footing profileissue; device 200, shown in FIG. 2, illustrates a T-top profile issue;device 300, shown in FIG. 3, illustrates an undercut profile issue; anddevice 400, shown in FIG. 4, illustrates a top rounding profile issue.Each profile is caused by an imbalance (e.g., too high or too lowrelative concentration) in one or more of the chemical components of thephotosensitive material at certain regions of a layer (e.g., top orbottom) formed of the material. This imbalance influences the solubilityof the photosensitive material the developer, and thus affects theresultant profile. The imbalance in chemical components may include animbalance in acid including photoacid generator (PAG), base including aquencher, and/or other chemical components. Each profile of FIGS. 1, 2,3, and 4 is discussed in further detail below.

With respect to FIG. 1, the device 100 illustrates a footing profileissue. When the radiation intensity in the exposure of a photoresistlayer is not sufficiently brought to a bottom region of the layer, afooting profile of the patterned feature may result. Similarly, afooting profile may result when there is an insufficient amount of acid(or the acid is captured) at the bottom regions of the photoresistlayer, such that residual photoresist remains after development. Thedevice 100 includes a resist feature 104 having a footing profile 106.

Weak radiation intensity at the bottom region of a photoresist layer maybe due to radiation being absorbed by the resist; radiation absorbed bythe underlying substrate (substrate 102) or radiation absorbeddifferently by different regions of the underlying substrate; radiationhaving insufficient intensity at a bottom region of a photoresist layerdue to topography of the substrate 102; introduction of poisons from thesubstrate 102 into the overlying photoresist layer that will reduce theamount of acid; and/or other affects. For example, if the PAG is notinitiated due to weak radiation intensity, the CAR reaction will bedecreased and the ALG will not leave after PEB. This can impact patternfidelity by causing a footing profile, such as footing profile 106. Inanother example, if a portion of the substrate has a lower reflectivity,the resist in and adjacent that area may suffer from a lower radiationintensity and leave a scum or a footing profile such as footing profile106 (for example, if a portion of the substrate interposing the features104 has a lower reflectivity, the sidewalls of the features 104 maysuffer from a footing profile 106 over that interposing region of thesubstrate 102). In yet another example, if a trench structure isdisposed in the substrate 102 interposing the photoresist features 104,photoresist may not be sufficiently removed from the sidewalls of thetrench due to lower radiation intensity reaching the trench area. Inanother example, the substrate 102 may include a film which can absorbthe photo acid and reduce the CAR reaction in the photoresist layer. Forexample, a nitride film of the substrate 102 may provide a danglingnitrogen bond that can cause the absorption of acid from the photoresistlayer.

With respect to FIG. 2, the device 200 illustrates a T-top profile issue(also referred to as a top bridge). The device 200 includes a resistfeature 104 having a T-top profile 202. When the PAG concentration isdecreased at the top region of a photoresist layer, a T-top profile mayresult. For example, the PAG concentration may be reduced at a surfaceof the photosensitive layer due to optical intensity differences betweenthe photoresist center region and photoresist top region; a surface PAGleaching into immersion fluid (e.g., water); an increase in surfacequencher concentration; a different photoresist polymer in the topregion of the layer as compared to the center region of the layer (e.g.,the different photoresist polymers may have a different dissolution rateto a developer); and/or other affects.

With respect to FIG. 3, the device 300 illustrates an undercut profileissue. When the PAG concentration is too great, relatively, at thebottom region of a photoresist layer, an undercut profile may result.The device 300 includes a resist feature 104 having an undercut profile302. The undercut profile 302 may result from a substrate than has alower film density that can influence the PAG/quencher loading balance.For example, the substrate 102 may absorb the quencher of thephotosensitive layer providing an imbalance in acid/base at the bottomregion of the photosensitive layer (e.g., a reduction in the quencher orbase concentration). Upon development of the resist, the undercut 302results. In another example, the substrate 102 may have an additionalacid that leaches into the resist and that complements the CAR reactioncausing an imbalance in acid/quencher at the bottom region of thephotosensitive layer (e.g., increasing the acid concentration). Thus,the undercut 302 to result from an additional acid concentration. In yetanother example, if the substrate 102 includes a layer having adifferent reflectivity (e.g., a film underlying the photoresist feature104 is higher than the film adjacent the feature 104), the profile of afeature on the higher reflectivity area may become undercut due to thestronger optical intensity provided by the increased reflectivity.

With respect to FIG. 4, the device 400 illustrates a top-roundingprofile issue. When the PAG concentration is higher than a quencherconcentration in a top region of the photoresist layer, the profile ofthe resultant feature will exhibit a top-rounding effect. The device 400includes a resist feature 104 having a top-rounding profile 402. Thetop-rounding profile 402 may be caused by various configurations of thephotosensitive material from which the resist feature 104 is patterned.For example, when the photoacid generator (PAG) concentration is higherthan a quencher concentration in a top region of a photosensitive layer,the top-rounding profile 402 may result. Acid contamination from anoverlying layer (e.g., an immersion top coat or top antireflectivecoating (TARC) film) may increase the acid concentration in a top regionof the photosensitive layer, which also may result in a top-roundingprofile such as the top-rounding profile 402. In using immersionlithography, if the immersion fluid (e.g., water) is absorbed by thephotosensitive material, the fluid (e.g., water) can change the aciddiffusion length and also affect the profile. If the acid has a highdiffusion length, the line-width profile will become thinner or atop-rounding profile may result.

The present disclosure discusses several methods and compositions thatmay be used to provide adequate balancing between acid or PAG loadingand base or quencher loading. These methods and/or compositions may beused in combination, or separately to pattern a substrate such as asemiconductor wafer. It is noted that although a method or compositionmay be discussed as targeting a specific issue, such as a specificprofile issue, the method and/or composition is not so limited and oneof ordinary skill would recognize other applications which would benefitfrom the disclosure.

In an embodiment, a photosensitive material is deposited having auniform composition such as illustrated in FIG. 5 by device 500 havingphotosensitive material 502. The photosensitive material 502 is disposedon a substrate 102. The substrate 102 may be a semiconductor substrate(e.g., wafer). In an embodiment, the substrate 102 is silicon in acrystalline structure. In alternative embodiments, the substrate 102 mayinclude other elementary semiconductors such as germanium, or includes acompound semiconductor such as, silicon carbide, gallium arsenide,indium arsenide, and indium phosphide. The substrate 102 may include asilicon on insulator (SOI) substrate, be strained/stressed forperformance enhancement, include epitaxially grown regions, includeisolation regions, include doped regions, include one or moresemiconductor devices or portions thereof, include conductive and/orinsulative layers, and/or include other suitable features and layers. Inan embodiment, the substrate 102 includes antireflective coatings, hardmask materials, and/or other target layers for patterning by thephotosensitive layer 502. In an embodiment, the substrate 102 is typicalof a CMOS process technology. However, though processing a substrate inthe form of a semiconductor wafer may be described, it is to beunderstood that other examples of substrates and processes may benefitfrom the present invention such as, for example, printed circuit boardsubstrates, damascene processes, and thin film transistor liquid crystaldisplay (TFT-LCD) substrates and processes.

The photosensitive material 502 may be positive tone or negative toneresist. In an embodiment, the photosensitive material 502 is chemicalamplified resist (CAR). As illustrated in FIG. 5, the photosensitivematerial 502 is substantially uniform distribution of quencher and/oracid. For example, the photosensitive material 502 may illustrate thematerial as initially deposited (e.g., seconds or fractions ofsections). However, due to the issues discussed above with respect toFIGS. 1-4, it may be desired for this normal distribution to be altered.

In FIG. 1 described above, a resist feature 104 having a footing profile106 is described. One compensation for such a profile is reducing theconcentration of base or quencher present at the bottom region of aphotosensitive material layer after forming the layer and prior toprocessing or patterning the layer (e.g., prior to exposure, etc). Suchcompensation may increase the concentration of base or quencher presentat the top region of a photosensitive material layer.

In an embodiment, if the quencher is modified to have a composition suchthat it will “float” or otherwise move towards a top surface of thephotosensitive material, it will reduce the quencher component availableat the bottom region of the photosensitive layer. This is illustrated bythe device 600 of FIG. 6 and the photosensitive layer 602. The quencher(illustrated by the dots) has moved to an upper region 606 of thephotosensitive layer 602 leaving a lower region 604 with a reducedquantity of quencher. This “floating” or movement of a quencher towardsa top surface can be accomplished in several ways. It is noted that this“floating” may occur automatically due to the composition of thephotosensitive materials and/or components of the material (e.g.,quencher formula) as discussed below. The “floating” may occursubstantially immediately after forming the layer (e.g., 0.1 second).

In an embodiment, a fluorine atom(s) is introduced to the quencherstructure. In another embodiment, another inert, relatively light atomis introduced instead of or in addition to fluorine. The fluorineatom(s) may be provided as an alkyl fluoride (C_(x)F_(y)). In anembodiment, the x coefficient in CxFy is between 1 and 10. In anembodiment, the alkyl fluoride may include CF₃, C₂F₅, C₃F₇, and/or othersuitable groups. Exemplary embodiments of photosensitive materialcompositions including quencher structure formulas, which may result inthe configuration of device 600 of FIG. 6 are discussed below. Thefluorine or other inert atom may cause the component to which it islinked to “float” to an upper portion of a layer as formed, as discussedabove.

In an embodiment, the quencher has the formula

where R³ includes a fluorine atom or alkyl fluoride. In an embodiment,the R³ includes an alkyl fluoride C_(x)F_(y) where x is between 1 and10. In an embodiment, the alkyl fluoride may include CF₃, C₂F₅, C₃F₇,and/or other suitable groups. R³ may be an alkyl group a plurality ofcarbon atoms (e.g., x between of 1 to 10) with a straight, branched orcyclic structure. The alkyl group may also include a hetero atom, suchas nitrogen or oxygen.

In another embodiment, the quencher has the formula

where R⁴, R⁵, and/or R⁶ include a fluorine atom or alkyl fluoride. R⁴,R⁵, and/or R⁵ may be an alkyl group a plurality of carbon atoms (x of 1to 10) with a straight, branched or cyclic structure. In an embodiment,the R⁴, R⁵, and/or R⁵ include an alkyl fluoride C_(x)F_(y). In anembodiment, x is between 1 and 10. In an embodiment, the alkyl fluoridemay include CF₃, C₂F₅, C₃F₇, and/or other suitable groups. The alkylgroup may also include a hetero atom, such as nitrogen or oxygen.

In an embodiment, the quencher has the formula

where R¹² includes a fluorine atom or alkyl fluoride. R¹² may be analkyl functional structure having a plurality of carbon atoms (x of 1 to10) with a straight, branched or cyclonic structure. In an embodiment,the R¹² include an alkyl fluoride C_(x)F_(y) where x is between 1 and10. In an embodiment, the alkyl fluoride may include CF₃, C₂F₅, C₃F₇,and/or other suitable groups.

In an embodiment, the quencher has the formula

where at least one of the R groups includes a fluorine atom or alkylfluoride. At least one of the R groups may be an alkyl functionalstructure having a plurality of carbon atoms (x of 1 to 10) with astraight, branched or cyclonic structure. In an embodiment, at least oneof the R groups includes an alkyl fluoride C_(x)F_(y) where x is between1 and 10. In an embodiment, the alkyl fluoride may include CF₃, C₂F₅,C₃F₇, and/or other suitable groups.

In an embodiment, the quencher has the formula:

where at least one of the R groups includes a fluorine atom or alkylfluoride. At least one of the R groups may be an alkyl functionalstructure having a plurality of carbon atoms (x of 1 to 10) with astraight, branched or cyclonic structure. In an embodiment, at least oneof the R groups includes an alkyl fluoride C_(x)F_(y) where x is between1 and 10. In an embodiment, the alkyl fluoride may include CF₃, C₂F₅,C₃F₇, and/or other suitable groups.

In an embodiment, the quencher copolymers with another polymer(s)(“associated polymer”) and modification of the associated polymer(s) issufficient to provide movement or floating of the quencher. For example,in an embodiment the copolymer formula

is provided. The polymer unit y may provide the quencher. The polymerunit x may provide the floating performance control. The polymer unit zmay provide the developer solubility control. Thus, modification of R1or R5 to include a fluorine atom (such as an alkyl fluoride) may allowfor the quencher distribution to increase at a top surface and/ordecrease at a bottom region of a deposited layer.

In an embodiment, a fluorine (alkyl fluoride) is linked to the polymerunit x, which is then referred to as the floating polymer unit. In suchan embodiment, the floating polymer unit x may be between 3% and 90% ofthe copolymer. In an embodiment, the polymer unit x may be between 30%and 70% of the copolymer. R1 may include a fluorine atom. The R1fluorine may include CmFn functional group. In an embodiment, m isbetween 1 and 10.

The functional group R5 may provide for solubility control. In anembodiment, R5 includes a lactone structure, alcohol structure,carboxylic structure and/or other structure for example providinghydrophilic-nature to developer and water. The quencher structure y mayalso include R2, R3 and R4 functional group. R2, R3 and R4 may include Hor alkyl groups. The alkyl groups may include carbon chain that isstraight, branched or cyclic in structure. In an embodiment, the carbonchain includes between 1 and 10 carbon atoms. The alkyl group may alsoinclude nitrogen or oxygen hetero atom. In an embodiment, the alkylgroup includes a double bond alkyl structure.

In another embodiment, a solvent of the photosensitive material isprovided such that it has a higher affinity to the quencher structure.The quencher may have a higher volatility. Thus, the quencher may floatto a top region of the photosensitive material layer after formation,for example, during solvent evaporation.

In yet another embodiment, a quencher composition may provide for adifferent polarity and/or affinity to another polymer of thephotosensitive material. Thus, when the associated polymer moves (e.g.,floats) to a region of the layer, the quencher may also move to theregion. This may allow other polymers to be modified, while maintaininga quencher formulation.

The embodiments discussed above may serve to improve the profile issuesdiscussed, for example the footing profile 106 of the device 100 of FIG.1 and/or the top rounding profile 402 of the device 400 of FIG. 4. Forexample, the floating quencher increases the base amount in the topprofile area of a formed photoresist feature, thus compensating for astronger relative acid loading in that region. Thus, as a result of thedevice 600 illustrated in FIG. 6, a straight wall feature such asfeature 702 of FIG. 7 may be provided.

In addition to or in lieu of the photosensitive material compositionsabove that allow for a base or quencher to be moved or “floated” to aregion (e.g., top surface) of a layer, the following discussion isapplied to the photosensitive material and the movement or “floating” ofan acid or photoacid generator (PAG) of the photosensitive material.

In FIG. 2 described above, a resist feature 104 exhibits a T-top profile202. One compensation for such a profile is increasing the concentrationof acid present at the top region of a photosensitive material layerafter forming the layer and prior to processing the layer (e.g., priorto exposure, etc). In FIG. 3 described above, a resist feature 104exhibiting an undercut profile 302 is illustrated. One compensation forsuch a profile is reducing the concentration of acid present at thebottom region of a photosensitive material layer after forming the layerand prior to processing the layer (e.g., prior to exposure, etc).

In an embodiment, if the photosensitive material is modified to have acomposition such that acid or PAG will “float” or otherwise move towardsa top surface of the photosensitive material, it will reduce the PAGcomponent available at the bottom region of the photosensitive layer.This is illustrated by FIG. 8 and the device 800 having a photosensitivelayer 802. The acid or PAG (illustrated by the dots 808) has moved to anupper region 806 of the photosensitive layer 802 leaving a lower region804 with a reduced quantity of acid or PAG. This is also illustrated byFIG. 9 and the device 900 having a photosensitive layer 902. The acid orPAG (illustrated by the dots 808) has moved to an upper region 806 ofthe photosensitive layer 802 leaving a lower region 804 with a reducedquantity of acid or PAG. Comparing device 900 and device 800,illustrated is that the relative size of regions is dependent upon theconcentration and/or composition of the photosensitive material. Forexample, in an embodiment the top region (e.g., 806) may beapproximately 80% of the layer. In another embodiment, the top region(e.g., 806) may be approximately 20% of the layer. Any configuration ispossible and within the scope of the present disclosure. (It is notedthat while illustrated as two “regions,” the concentration of thecomponent may be gradated.) The “floating” or movement of an acid or PAGtowards a top surface can be accomplished in several ways. It is notedthat this “floating” may occur automatically due to the composition ofthe photosensitive materials and/or components of the material (e.g.,PAG or acid formula). The “floating” may occur substantially immediatelyafter forming the layer (e.g., 0.1 second).

In an embodiment, a fluorine atom(s) is introduced to the acid or PAGstructure. In another embodiment, another inert, relatively light atomis introduced instead of or in addition to fluorine. The fluorineatom(s) may be provided as an alkyl fluoride (C_(x)F_(y)). In anembodiment, the alkyl fluoride may include CF₃, C₂F₅, C₃F₇, and/or othersuitable groups. Exemplary embodiments of photosensitive materialcompositions including acid or PAG formulas, which may result in theconfiguration of device 800 and/or 900 are discussed below.

In an embodiment, the PAG has the formula

where R1⁻ is an anion unit. R1⁻ may be a liner structure, a branchstructure, a cyclic structure and/or other suitable structure. At leastone alkyl fluoride functional unit is linked to the R group. The alkylfluoride functional group may assist in floating the acid to a topregion of an as-formed layer. In an embodiment, the alkyl fluoride mayinclude CF₃, C₂F₅, C₃F₇, and/or other suitable groups. In an embodiment,the alkyl fluoride includes at least two carbon atoms. In an embodiment,C₂F₅ is provided in R1⁻. In an embodiment, two alkyl fluoride groups areincluded in R1⁻. In an embodiment, the alkyl fluoride group is linked toone of the —CH₂— groups for floating improvement.

The R2, R3, and R4 groups in the PAG above may each be independentlyhydrogen or a straight, branched, or cyclic monivalent C1-C20hydrocarbon groups. In an embodiment, the R2, R3, R4 include an alkylgroup or alkoxy group, which may include a heteroatom. Examples ofhydrocarbon groups including a heteroatom include but are not limited tomethyl, ethyl, propyl, isopropyl, n-hexyl, sec-butyl, tert-butyl,tert-amyl, n-pentyl, cyclopentyl, and/or other hydrocarbons. Furtherdescription of PAG components is provided in U.S. Pat. No. 7,670,751,which is hereby incorporated by reference.

In an embodiment, the PAG has the formula

The PAG may be a linear anionic PAG. As illustrated, the anionic unit isC₄F₉SO₃—; however other compositions are possible. In an embodiment, toimprove the floating ability of the PAG, the carbon fluorideconcentration is increased for example to C₅F₁₁SO₃—.

In an embodiment, the PAG of the photosensitive material has the formula

The PAG may be a linear anionic PAG. R¹ may be straight, branch, cyclicand/or other structure. In an embodiment, the n unit of the —(CH₂)n- maybe between 1 and 10. R², R³, R⁴ may be benzyl group or benzyl group withsubstitutes. For example, the cation (R², R³, R⁴) may betriphenylsolfonium (TPS) or biphenylsolfonium (BPS). To providefloatability to the PAG at least one alkyl fluoride functional unit islinked to R¹. For example, in an embodiment, R¹ is provided with twoalkyl fluoride groups attached in a cyclohexane ring having the formula

Rf1 and Rf2 may be linked at ortho, meta, and/or para positions to eachother in the ring. The alkyl fluoride group may also be attached to theCH₂ group. In an embodiment, the alkyl fluoride, Rf1 and/or Rf2, mayinclude CF₃, C₂F₅, C₃F₇, and/or other suitable groups.

In an embodiment, the PAG has the formula

The PAG may be a linear anionic PAG. R may be alkyl or alkyl fluoride.In an embodiment, R includes C₂F₂, C₃F₇, and/or other suitable group. Rmay be straight, branch, cyclic with alkyl, or alkyl with O, N, or Shetero atoms, and/or other structure. In an embodiment, the n unit ofthe —(CH₂)n- may be between 1 and 10. The A1 may be an ester bond, etherbon, thioether bond, amid bond, carbonate bond, and/or other suitablebond. R², R³, R⁴ may be benzyl group or benzyl group with substitutes.For example, the cation (R², R³, R⁴) may be triphenylsolfonium (TPS) orbiphenylsolfonium (BPS). For floating ability, alkyl fluoride may beattached to the R group (e.g., at least two alkyl fluorides). Forexample, an alkyl fluoride attached anionic PAG may include the formula

or alternatively the formula

where each of the above formulas has two alkyl fluorides attached inadmantyl group to provide additional floating properties for thecomponent. The attached position of the alkyl fluoride groups in theformulas varies based on suitable design choices.

In the embodiments of PAG discussed above, an anion unit is providedthat includes a fluorine atom or alkyl fluoride group. This may enhancefloatability of the PAG. Alternatively, and/or additionally, a cationstructure may be provided that includes a fluorine atom or alkylfluoride group. This may also enhance floatability of the PAG. Exemplaryembodiments are discussed below.

In an embodiment, a TPS or BPS cation is modified to include a fluorineatom. For example, in an embodiment, at least two alkyl fluoride groupsare synthesized onto a TPS or BPS structure. The alkyl fluoride groupsmay be linked to a benzyl group.

For example, in an embodiment, the PAG has the formula

As illustrated, the PAG includes alkyl fluoride groups linked to cationPAG. The alkyl fluoride groups may include any alkyl fluoride CxFy wherex is between 1 and 10. In an embodiment, the alkyl fluoride may includeCF₃, C₂F₅, C₃F₇, C₄F₉, and/or other suitable groups.

In another example, in an embodiment, the PAG has the formula

As illustrated, the PAG includes alkyl fluoride groups linked to cationPAG. The cation PAG includes an alkyl group. The alkyl fluoride groupsmay include any alkyl fluoride C_(x)F_(y) where x is between 1 and 10.In an embodiment, the alkyl fluoride may include CF₃, C₂F₅, C₃F₇, C₄F₉,and/or other suitable groups.

The embodiments discussed above provide for fluorine or alkyl fluoridegroups to be linked to a PAG component. In certain embodiments, thealkyl fluoride group is linked to the anion unit. In other embodiments,the alkyl fluoride group is liked to the cation group. The addition ofthe alkyl fluoride group may serve to modify the distribution of the PAGcomponent in the as-formed photosensitive material layer. This may beused to improve the profile issues discussed, for example the undercutprofile 302 of the device 300 of FIG. 3 and/or the T-top profile 202 ofthe device 200 of FIG. 2. For example, the floating PAG increases theacid amount in the top profile area of a formed photoresist feature thuscompensating for a stronger acid loading in that region. Thus, as aresult a straight wall feature such as feature 702 of FIG. 7 may beprovided.

In an embodiment, more than one composition of PAG may be provided in aphotosensitive material. The compositions of the PAG may vary and/or bedirected to specific functions. For example, in an embodiment, a PAGwith an alkyl fluoride group linked thereto is provided for floatingpurposes and a conventional PAG is also included in the photosensitivematerial.

It is noted that the quencher and/or PAG compositions discussed aboveprovide exemplary embodiments only and are not intended to be limitingto the application of the present disclosure. For example additionalstructures which may benefit from the substitution and/or provision offluorine and/or alkyl fluoride groups now known or later developed maybe recognized. Various examples are provided, for example, in U.S.Patent Application No. 2008/0153036, which is hereby incorporated byreference.

Similarly, the present disclosure is not limited to quencher or PAGcompositions, but to various components included in photosensitivematerial. These components include, for example, photo base generators(PBG), photo decompose quenchers (PDQ) and/or other components. In anembodiment, nitrogen containing organic base compounds may be providedthat include alkyl fluoride groups for improved floating properties.Further examples are provided in U.S. Patent Application 2010/0304297which is hereby incorporated by reference and describes components thatmay be modified to include alkyl fluoride groups as discussed herein.

Yet another application of the present disclosure is a treatment methodthat is capable of reducing the so-called side lobe printing outphenomena. As the critical dimensions of devices shrink, this reducesthe process window for lithography and makes the lithography processmore challenging to produce an adequate resist features. For example,small features in a pattern can cause a side lobe effect, which resultsin undesired features being imaged onto a substrate. During irradiationof a main feature intended to printed on to the substrate, the side lobeeffect may provide for a radiation, though weaker than the main imagedfeatures, to be incident on the substrate in unwanted areas. Thisprovides for a small amount of photoacid to be generated (e.g., near thesurface of the photoresist layer) in unwanted areas. This photoacid isundesirable because left untreated, it will form unwanted features inthe developed resist.

Thus, the present methods and compositions may be provided to neutralizethe unwanted acid. For example, an additional floating base component inthe photosensitive material may serve to quench the acid created in theside lobe phenomena. The acid may be quenched by providing a floatingquencher, a floating amine component, a floating PDQ, a floating PBG,and/or other basic component.

Referring now to FIG. 10, illustrated is a method 1000 that provides amethod of forming a pattern in a photosensitive material layer. Themethod 1000 begins at block 1002 where a profile issue for a resultantphotosensitive layer is determined. The profile issue may besubstantially similar to one or more of the profiles discussed abovewith reference to FIGS. 1-4. For example, in an embodiment, thephotosensitive layer is determined to have a footing issue (see, e.g.,the device 100 described above with reference to FIG. 1). In anembodiment, the photosensitive layer is determined to have a T-topprofile issue (see, e.g., the device 200 described above with referenceto FIG. 2). In an embodiment, the photosensitive layer is determined tohave an undercut profile issue (see, e.g., the device 300 describedabove with reference to FIG. 3). In an embodiment, the photosensitivelayer is determined to have a top rounding profile issue (see, e.g., thedevice 400 described above with reference to FIG. 4).

The profile issue may arise from the photosensitive material, thephotolithography equipment, the underlying layer(s) such as a bottomantireflective coating, the overlying layer(s) such as a topantireflective coating, the pattern type (e.g., aspect ratio), and/orother factors such as those discussed above with reference to FIGS. 1-4.The profile issue may be determined from test chips, previous productresults, simulation results, data analysis, and/or other suitablemethods. It is noted that the profile issue is determined prior to theformation of the layer on the device describes in the method 1000.

The method 1000 then proceeds to block 1004 where the compensationstrategy is determined. The compensation strategy may includealterations to the photosensitive material composition to provide forreduction and/or correction of the profile issue described above. Forexample, the compensation strategy may be provided to increase thefidelity of the patterned photosensitive layer and/or provide animproved lateral sidewall of a feature of the patterned photosensitivelayer. In an embodiment, the compensation strategy includes increasingor decreasing acid or PAG concentration at one portion (e.g., upper orlower) of the deposited photosensitive layer. In an embodiment, thecompensation strategy includes increasing or decreasing the quencher orbase concentration at one portion (e.g., upper or lower) of thedeposited photosensitive layer.

The method 1000 then proceeds to block 1006 where a photosensitivematerial formulation (e.g., composition) is determined and provided toaddress the compensation strategy. In an embodiment, a photosensitivematerial formulation to provide for increased acid or PAG at a topportion of a deposited photosensitive material layer is determined. Inan embodiment, a photosensitive material formulation to provide forincreased acid or PAG at a bottom portion of a deposited photosensitivematerial layer is determined. In an embodiment, a photosensitivematerial formulation to provide for increased base or quencher at a topportion of a deposited photosensitive material layer is determined. Inan embodiment, a photosensitive material formulation to provide forincreased base or quencher at a bottom portion of a depositedphotosensitive material layer is determined.

The photosensitive material composition or formulation provided in block1006 may be substantially similar to the compositions discussed abovewith reference to FIGS. 5, 6, 7, 8, and 9 and the accompanyingdescription(s).

The method 1000 then proceeds to block 1008 where the photosensitivematerial is applied to a substrate. The photosensitive material appliedmay include the formulation developed in block 1006 of the method 1000,described above.

The substrate may be a semiconductor substrate (e.g., wafer). In anembodiment, the substrate is silicon in a crystalline structure. Inalternative embodiments, the substrate may include other elementarysemiconductors such as germanium, or includes a compound semiconductorsuch as, silicon carbide, gallium arsenide, indium arsenide, and indiumphosphide. The substrate may include a silicon on insulator (SOI)substrate, be strained/stressed for performance enhancement, includeepitaxially grown regions, include isolation regions, include dopedregions, include one or more semiconductor devices or portions thereof,include conductive and/or insulative layers, and/or include othersuitable features and layers. In an embodiment, the substrate is typicalof a CMOS process technology. However, though processing a substrate inthe form of a semiconductor wafer may be described, it is to beunderstood that other examples of substrates and processes may benefitfrom the present invention such as, for example, printed circuit boardsubstrates, damascene processes, and thin film transistor liquid crystaldisplay (TFT-LCD) substrates and processes.

The photosensitive material layer may be formed by processes such ascoating (e.g., spin-on coating) and soft baking. In an embodiment, thephotosensitive material layer is formed on a bottom anti-reflectivecoating layer (BARC).

The method 1000 then proceeds to block 1010 where the substrate isirradiated. The method may use various and/or varying wavelengths ofradiation to expose the energy-sensitive photosensitive layer, describedabove with reference to blocks 1006 and 1008. In an embodiment, thesubstrate is irradiated using ultraviolet (UV) radiation or extremeultraviolet (EUV) radiation. The radiation beam may additionally oralternatively include other radiation beams such as ion beam, x-ray,extreme ultraviolet, deep ultraviolet, and other proper radiationenergy. Exemplary radiation includes a 248 nm beam from a kryptonfluoride (KrF) excimer laser, a 193 nm beam from an argon fluoride (ArF)excimer laser, and/or other suitable wavelength radiations. In anexample, the photo-acid generator (PAG) that generates acid during theexposure process changes the solubility of the exposed/non-exposedmaterial. Lithography processes used to pattern the photosensitivematerial layer include immersion lithography, photolithography, opticallithography and/or other patterning methods which may transfer a patternonto the photosensitive layer.

After exposure, a post-exposure bake (PEB) process may be performed.During the baking process, the photoresist layer is provided at anelevated temperature. This may allow more acid to be generated from thephoto-generated acids through a chemical amplification process.

The photosensitive material layer, after exposure to a pattern, may bedeveloped. The developing may form a patterned photoresist layerincluding a plurality of masking elements or features, such as describedabove with reference to FIG. 7. During the developing process, adeveloping solution is applied to the photosensitive material layer. Inone embodiment, the photosensitive material that was exposed to theradiation is removed by the developing solution (developer). However, anegative-type resist is also possible. The developing solution may be apositive tone developer or negative tone developer. One exemplarydeveloper is aqueous tetramethylammonium hydroxide (TMAH).

The method may proceed to rinsing, drying, and/or other suitableprocesses. The patterned photosensitive layer may be used as a maskingelement in performing one or more processes on underlying layers such asetching, ion implantation, deposition, and/or other suitable processesincluding those typical of a CMOS-compatible process. The photosensitivematerial layer may be subsequently stripped from the substrate.

In summary, the methods and devices disclosed herein provide for movinga component of a multi-component photosensitive material to a desiredregion of a layer formed by the photosensitive material. In doing so,embodiments of the present disclosure offer advantages over prior artdevices. Advantages of some embodiments of the present disclosureinclude providing increased fidelity of the pattern and substantiallylinear sidewalls of a feature patterned from the photosensitivematerial. For example, acids and/or bases may be moved such that thedesired balance between components is provided in a layer prior topatterning. Some embodiments of the present disclosure may also beapplied to solve other issues where it may be beneficial for onecomponent to be unequally distributed, or to account for a naturallyoccurring undesired distribution between components. In one embodiment,a component desired to be positioned near the top of a feature isprovided with fluorine atoms such as in the form of alkyl fluoridegroups that cause it to “float” to the top of a formed layer. Based ondesign considerations, the component chosen for “floating” and thequality required may be determined. It is understood that differentembodiments disclosed herein offer different disclosure, and that theymay make various changes, substitutions and alterations herein withoutdeparting from the spirit and scope of the present disclosure. Thus,provided in one embodiment is a photosensitive material including asolvent; a photoacid generator (PAG) component; and a quenchercomponent. At least one of the PAG and the quencher may include an alkylfluoride group. In another embodiment of a photosensitive material,another component (in addition to or in lieu of PAG or quencher) isdetermined to “float” to an upper region of an as-formed layer and afluorine or alkyl fluorine group is included in that component.

In another embodiment, a method of forming pattern on a substrate isprovided. The method includes providing a semiconductor substrate andforming a photosensitive layer on the semiconductor substrate. Thephotosensitive layer includes a first component having a fluorine atom.After forming the photosensitive layer, the first component is floatedto a top surface of the photosensitive layer. Thereafter, thephotosensitive layer is patterned. The first component may include aphotoacid generator (PAG), a quencher, a photo base generator (PBG), aphoto decompose quencher (PDQ), an alkyl fluoride group, a C₂F₅ group,and/or other suitable components as described above. In yet anotherembodiment, a method of fabricating a semiconductor device is provided.The method includes determining a profile issue associated withformation of a first feature. A formation is then determined for aphotosensitive material to compensate for the determined profile issue.A layer of the photosensitive material is formed having the determinedphotosensitive material formulation on a substrate. The layer of thephotosensitive material is then patterned to provide the first feature.

What is claimed is:
 1. A method, comprising: providing a photosensitivematerial that includes a solvent, a photoacid generator, and a quencherhaving an alkyl fluoride group of C₂F₅ linked to the quencher;depositing the photosensitive material onto a semiconductor substrate;while the photosensitive material is disposed on the semiconductorsubstrate, floating the quencher having the alkyl functional group ofC₂F₅ from a lower region to an upper region of a layer comprising thephotosensitive material, wherein the floating quencher has the formula

wherein R4, R5 and R6 are alkyl fluoride and one of R4, R5, and R6 isthe C₂F₅ component; thereafter, exposing the layer of photosensitivematerial to a radiation beam; wherein the upper region has a loweramount of acid from the photoacid generator than the lower region afterthe exposing of the layer; and developing the exposed layer.
 2. Themethod of claim 1, further comprising: determining a concentration ofthe quencher such that the developing includes forming substantiallyvertical sidewalls.
 3. The method of claim 1, wherein the R4 is the C₂F₅component.
 4. The method of claim 1, wherein the R5 is the C₂F₅component.
 5. The method of claim 1, wherein the R6 is the C₂F₅component.
 6. A method, comprising: providing a photosensitive materialthat includes a solvent, a photoacid generator, and a quencher having analkyl fluoride group linked to the quencher; depositing thephotosensitive material onto a semiconductor substrate; while thephotosensitive material is disposed on the semiconductor substrate,floating the quencher having the alkyl functional group of C₂F₅ from alower region to an upper region of a layer comprising the photosensitivematerial, wherein the floating quencher has the formula

wherein R¹² has the C₂F₅ component, thereafter, exposing the layer ofphotosensitive material to a radiation beam; wherein the upper regionhas a lower amount of acid than the lower region after the exposing ofthe layer; and developing the exposed layer.
 7. The method of claim 6,further comprising: determining a concentration of the quencher suchthat the developing includes forming substantially vertical sidewalls.8. The method of claim 6, wherein the photosensitive material furtherincludes a solvent.